Iowa Core K-12 Mathematics (PDF) - Green Hills AEA

Mathematics | Grade 1
In Grade 1, instructional time should focus on four critical areas: (1) developing understanding
of addition, subtraction, and strategies for addition and subtraction within 20; (2) developing
understanding of whole number relationships and place value, including grouping in tens and
ones; (3) developing understanding of linear measurement and measuring lengths as iterating
length units; and (4) reasoning about attributes of, and composing and decomposing geometric
shapes.
(1) Students develop strategies for adding and subtracting whole numbers based on their prior work with
small numbers. They use a variety of models, including discrete objects and length-based models (e.g.,
cubes connected to form lengths), to model add-to, take-from, put-together, take-apart, and compare
situations to develop meaning for the operations of addition and subtraction, and to develop strategies to
solve arithmetic problems with these operations. Students understand connections between counting
and addition and subtraction (e.g., adding two is the same as counting on two). They use properties of
addition to add whole numbers and to create and use increasingly sophisticated strategies based on these
properties (e.g., "making tens") to solve addition and subtraction problems within 20. By comparing a
variety of solution strategies, children build their understanding of the relationship between addition and
subtraction.
(2) Students develop, discuss, and use efficient, accurate, and generalizable methods to add within 100
and subtract multiples of 10. They compare whole numbers (at least to 100) to develop understanding of
and solve problems involving their relative sizes. They think of whole numbers between 10 and 100 in
terms of tens and ones (especially recognizing the numbers 11 to 19 as composed of a ten and some
ones). Through activities that build number sense, they understand the order of the counting numbers
and their relative magnitudes.
(3) Students develop an understanding of the meaning and processes of measurement, including
underlying concepts such as iterating (the mental activity of building up the length of an object with
equal-sized units) and the transitivity principle for indirect measurement. 1
(4) Students compose and decompose plane or solid figures (e.g., put two triangles together to make a
quadrilateral) and build understanding of part-whole relationships as well as the properties of the original
and composite shapes. As they combine shapes, they recognize them from different perspectives and
orientations, describe their geometric attributes, and determine how they are alike and different, to
develop the background for measurement and for initial understandings of properties such as congruence
and symmetry.
1 Students should apply the principle of transitivity of measurement to make indirect comparisons, but they need
not use this technical term.
Disclaimer: This document is up-to-date as of 11/17/2010. The language provided may not be Page 15 of 98
modified in any way. The most current Iowa Core can be found at http://iowacore.educateiowa.gov.